I'm a 54 year old female. I was given Doxycycline to help treat ...

I'm a 54 year old female. I was given Doxycycline to help treat what may be Interstitial Cystitis - bladder inflamation of unknown origin. Within 20 minutes of taking, I felt like it crossed the blood-brain barrier. I would get a weird dizzy/nausea sensation. I only took it for 10 days and I was so glad to be done as I hated how I felt while on it. What I'm worried about now and this is why I wound up on this site, is that it feels like it is still in my system a week after finishing it. After every meal, my stomach hurts. I've been having headaches --which I don't typically have. I'm having trouble concentrating and focusing on work that I have to do and feeling suddenly sleepy for no good reason. I struggled for years with depression, but have felt relatively good for the last 10 years--I never took any depression meds. Since taking this drug, I have sensations of sadness and hopelessness like I haven't felt in years. I'm worried about the time it's taking for this drug to leave my system and whether it's done some kind of permanent damage.