I am a 19 year old currently attending university. When I was in around 6th or 7th grade I was diagnosed with ADHD [don't know if this is relevant for what's to follow].

Over the past two years I've been experiencing what I thought to be depressive like symptoms. I even went to a therapist and I don't think the whole experience was for me. Thinking it would just pass I stopped attending the therapist (this was earlier this year). Again, the therapy wasn't very helpful. Eventually what I was feeling passed, or at least I thought it did. Every so often I'd experience episodes of very depressive thoughts ranging from feeling extremely lonely and disconnected sometimes angry, and feeling as if no one understood me. However, I am very much not lonely and I am aware of this but the thoughts still consume me during those moments. When these episodes happen I'd essentially have a break down and try to get away from anyone I was with at that moment so that no one saw me. 
But eventually the waves of depressive and angry thoughts would pass and I'd 
be alright. I've had a few of these episodes, and just had one about 15 minutes ago, and it's getting to the point where I don't know how to handle it anymore. I don't want them to escalate and I don't know what it is. 


A lot of times I feel elated and happy, or at least I feel like I do until I have these episodes. I also feel its fair to mention that I don't handle big social situations well (socials,parties) (I'm heavily introverted), and feel that I have difficulty finding the courage to speak to people at times. That being said, in high school and among my group of friends I am considered the loud, and funny one and I can agree with that as that's the person I always put on display around them. 


I've always usually kept how I feel on the inside except for a certain few people, but talking about it with them doesn't seem to do anything for me anymore


Is it possible that it's just stress? Although there isn't anything I'm really stressed out about. University is difficult yes, but I don't stress over it too much.  