Sick Kitten losing weight then gains it back quickly

Motley is a 5-6 month old female kitten (breed unknown) when I got her the vet said she had a heart murmur. Her weight has always been a little under what it should but according to the vet she wasn't dangerously skinny. She has always had a few weird habits like eating the litter, eating poop, she has urinated in her water/food dish (this only happened once when she was 2mo) she loves to lick water off of our wood deck, you get the picture. Well my boyfriend and I left her with his mom for 4 days and when we came back we got the report that she had stopped eating 2 days after we left. Since she is already very small, this weight loss had her looking very unhealthy. She also could not use her back legs yesterday at all.. According to my bf's mom, she has made significant improvement since we got home. She has eaten a whole can of kitten wet food and has even run a few times. Does anyone have any idea what is going on? Did she just have a little separation anxiety and she's all better now that we are home? Or is this something that we need to get her to the vet for first thing in the morning?? Please help us figure out what's wrong with our little girl!! Thanks!

I'm sorry Motley isn't feeling well.

It is possible Motley stopped eating because of separation anxiety; but her not being able to use her back legs is really cause for concern--and a trip to the vets.

Did your vet say what the cause is of a heart murmur, and low weight?

Vibes for Motley.

The vet did not say what has caused the murmur but we think she is under weight bc she was the runt of the litter.. no other explanation really. She hasn't seemed to make progress since last night except for the fact that she was wanting to eat dry food today. Her legs are still shaky and she is still sleeping and laying around a lot. I did notice that when I touch one of her back legs, she gets upset with me. If I touch the other back leg it doesn't seem to bother her. This situation is stressin me out!! Can't seem to find an explanation for whats going on... hope she gets better.
 

She may have injured her leg when you weren't around her.

Were I you, I'd take her to the vets.