I feel so sick

Lately I’ve been feeling so sick nauseous have a horrible headache yadda yadda. I drink more than enough liquids I’m eating enough my back is hurting more than usual... I often have these problems because of the meds I’m on & ive been on them for like 7 years but I just feel so much worse lately. I’m 16 weeks PP yes I have sex but I’ve been on birth control since the day after my son was born. Idk what it could be! Also I’m just so fricken tired! Any ideas on what could be wrong?