4 week old baby parrotlet is unwell and his poop is black and sticky and very big

Apologies for the long message, I tend to ramble on a lot and I wanted to state everything that happened if it is helpful. Last night our baby bird was acting as usual. He was learning to flap his wings, always wanted attention. He sat with us a lot and seemed fine. In the evening my husband noticed the bird had a black poop. It was thin. His poops earlier that day had all been normal I believe. The rest of the night he kept having thin black poops. Slightly dry. At night he got really sleepy after eating and needed to rest his head on my hand a lot (This didn’t worry me at the time because his head got tired the night before too but he was active the next day again). But last night his wings were hanging down a bit. I wasn’t sure if he was just too tired to hold them up. I went to put him to bed and that got him going again. He was trying to jump back out of the cage like crazy. So I held him a bit longer. He seemed well. I didn’t give him a new hot pack right before bed since I had given him a new one around the evening. He started getting too active to stay near his hot sock during the day so I didn’t get him a new ready until later. In the morning today my husband said he felt cold. The sock probably didn’t last the whole night (we are living in Taiwan so the winter night isn’t quite as cold as Canada where I’m from. Maybe I didn’t worry enough. Although I usually worry too much. I also worry about his hot sock making too much heat in his box, because it gets pretty warm in there?) I noticed his beak lost color too. He couldn’t hold his head up probably and couldn’t use his legs. He started crying a ton when he saw my husband but before he checked on him he was quiet. My husband held the bird in his hand for a while to give it warmth. His hands are always very warm and mine are always very cold, so I can’t help. He closed his eyes for a long time and his body was limp. We thought he died. My husband held him for a while longer and finally felt the bird move. After another 10-20 minutes or so the bird came to life a bit more. He had a massive poop. It was black, very sticky. The black was extremely large. There was a lot more white than usual too. The white didn’t seem very wet. My husband wants to keep the bird warm for a while before we head the vet. He is worried the bird will get cold again on the way.

I am wondering if it could be:

• He got too cold at night • He is hungry (I did not feel well in the morning today and had trouble getting myself up, so he was a couple hours late for his food) • He is dehydrated (I added a bit extra water to his cooked millet yesterday though) • Constipation • Some sort of parasite or worm • Blood in his intestine or kidney problem

As I’m finishing my post my husband informed me the bird has started walking again, thank goodness. He held the bird to give it warmth for around 1 1/2 to 2 hours. He is now able to stand up on his finger. And he was able to eat some food. He wants the rest of his meal, but I’m scared of over doing it while his body is unwell? His head is much better but it doesn’t seem 100% yet. And his wings are hanging down quite a bit. He is able to position them normally, but doesn’t seem to always want to. He just had quite a few very watery poops. They are green. How did this happen so fast? He just had a massive sticky black poop prior.

I believe my biggest mistake was not getting him a new hot pack at bed time. But I’m still worried about his wings and his poops. Could his wings be hanging out more because he has been trying to fly recently? I don’t remember him getting hurt while jumping around. I am going to start waking up during nights to check on him and give him an extra meal. Please tell me anything I could be doing better. I feel so terrible he is being so sweet with me now, without even knowing it was probably me that caused him to feel so unwell in the first place 😞

The pictures of his poops starts from the big sticky one in the morning until now where they are getting waterier

And yes he is young. There were no older parrotlets. The bird store owner made it sound so easy. Said he only needed to eat twice a day. He only needed a hot pack once in a while but not always. Of course we did a lot of research after coming home and changed some things. Also the bird store owner had him on “baby millet”. We are cooking it with water to soften it. Is this okay for his age? The owner said he’s “almost 4 weeks”. He could have been 3.5 weeks. The owner could have taken him off of formula a while before we even bought him. Should I be changing his food to formula? I want to give him cucumber for extra water. Is he too young to eat it? We’ve had the bird about 4 or 5 days now