Dealing with Extreme Fatigue and Nausea

Hi everyone! For some time now, I've been battling extreme fatigue and every now and then nausea. My appetite isn't as big as it used to be, which isn't a bad thing since I need to lose more weight (I've lost 35 lbs in the past year and a half). My doctor can't seem to find a reason for my symptoms. She ran blood tests and my vitamin D was extremely low so I've been taking vitamin D supplements. I also take vitamin B. We discussed if it's possible it's not a physical thing and maybe a mental thing since I suffer from anxiety and depression, so a month ago I started medication for that. I just want to stop being tired all the time. I have a 6 year old son, who's last day of school was Thursday. He's autistic and super active. I want to be able to do things with him and not be tired. Anyone else have a similar experience?