I don't even know what I've done, but I feel guilty

I'm sorry for my grammar, English isn't my first language.
So, I have a really close friend. Our emotional connection is the strongest bound I ever had with another person in my whole life, and as far as I'm concerned he feels the same way towards me. But during last several months our relationship is gradually going downhill, because we both have mental issues and our issues clash, we're in desperate need of opposite things. Several days ago we had our biggest fight of all times. We met a mutual female friend, and my best friend suddenly felt uncomfortable around her and tried to convince me to never talk to her again due to his unreasonable anxiety. When I refused to follow his instructions, he triggered me, and later admitted the fact he did it on purpose, so I'll learn a lesson by being hurt. After three hours of both of us throwing tantrums in a fit of passion, we were finally able to apologize to each other and make it up.
Then we both were behaving like nothing happened for a couple of days. Nothing outstanding happened, we didn't even met in person during that time. And them he called me out of the blue sounding deeply offended and upset and said he doesn't want to talk to me or see me for some time. He refused to give me at least a hint to what was wrong. He just blocked me off.
I can't eat, I can't sleep, I can't do anything but thinking "what I've done? What I've done? What I've done?". I analyzed and overanalyzed my every word and action during last several days, and I still have no clue. I feel terribly guilty, but I can't apologize properly because I don't even know what's wrong. I also feel lonely, scared and extremely insecure...Please, help. What do I do? How do I fix everything?
Thank you very much for reading this.

If you do not know that you have done anything wrong, perhaps it would help to tell yourself to set the worrying about it to the side (put it on hold) for a little while until you can ask your friend what it is he thinks you have done.
You are torturing your brain with too little information to go on. If these bad feelings come up try to tell yourself that you will deal with it when you have more information, but until then there is no reason to think about it.

I hope that gives you at least a little relief. Let me know how things go?

John