Took Doxycycline for 3 years - can this cause permanent anxiety?

There are alot of posts from people who have experienced anxiety during and after taking Doxycycline. I took it for 3 years to clear up some acne and around the time I started the Doxy I also developed anxiety.  I can remember days during that time that I literally thought I was going crazy. I didn't know what was going on with me but I never thought it was caused by the medication because it was not listed as a side effect. I was 21 when I began taking Doxy and I was transfering to different schools and trying to figure out who I was and what I wanted to do with me life. In general it was just a turbulent time in my life so it's not like one day I was OK and the next day I was anxious as far as I can remember. I was pretty well adjusted as a kid and teenager but experienced anxiety in some social situations and was depressed from time to time. But I always made friends pretty easily and enjoyed most social interaction. Anyway, I'm now 37 and I still suffer from anxiety - both generalized and social anxiety. While I've improved alot with therapy my brain just seems permanently altered by this condition and it still greatly effects my life. It feels very chemical - it's like no matter how hard I try to alter my thoughts and behavior there is just no kicking this and I think that it's largely chemical - the serotonin seems to be pretty depleted in my brain. Does anyone know - is it possible that taking the Doxycycline triggered these changes in my brain? Is taking Doxycycline a major factor in why I still continue to suffer from anxiety? Thanks!