Missing blood?

So I started going on the shot and I was supposed to take another one in February but missed it and so I just decided to get off of it again and wait and get it later after track season ended. So it’s been about 3 months since I’ve bleed from my 🐱 and I don’t know if I should go to the doctor for it because I’m having all the other side affects of a period with it. and I haven’t been sexually active since December and I’m not showing signs of pregnancy. And my back just started breaking out today. And I’m slowly starting to freak out about it. Help.