Weight loss due to...... STD?

Long short, I’ve had unprotected sex with someone. Like a year ago. Ever since then, I’ve been losing weight. I got tested in January, everything came back negative and I have antibodies against hepatitis... Which means I’m immune to that disease for life. But I definitely caught it at some point after that encounter. I know it came from it because it was my first time.

My question is: WHY THE FUCK DO I KEEP LOSING WEIGHT THEN?

I mean, it’s not really the weight, it’s more of a fat percentage type of thing. I keep getting more and more boney — and my current partner is, too, which makes me sad. So, why?

Also I feel like my muscles and my bones are getting weaker and weaker. Everytime I rotate my left ankle for example it keeps popping, kind of like when you’re popping your own knuckles. I’ve never, ever experienced something like this and it’s scary.

Has anyone gone through something similar?