Well, the intense anxiety attacks and depression sounds like just those things to me: anxiety and depression. And if those symptoms reared their head after your LSD experience (which I'm assuming was your first?), I would say they're directly related to your trip.
Could you perhaps explain some of the more intense parts of the trip? How much L did you take?
It's weird to think about, but chemicals in our body are constantly bonding to one another and compounds are being created and destroyed all the time. So, my theory is, when you throw in another, simple chemical (most popular drugs aren't very complex if you look at a model of them compared to another substance) into the mix, the elements in the drug will bind to your body's chemicals and will literally change your body's chemistry. This isn't permanent, but the thoughts and the way you perceive your situation are up to you and your super ego......or whatever allows you to analyze your personal thoughts....to sort out.
As others have already said, different doors in the mind are opened by different drugs. They will eventually close on their own, so to speak. But what could've come in while they were open? You already know what made it in, huh? lol, metaphors
Now, the only real opinion I could offer you is to do some deep internet searching, lurking, and posting on different medical sites and maybe even some other harm reduction sites. If I were in your shoes (and I have been numerous times), I would identify what I'm having trouble responding to, or responding slowly to, and look for information pertaining to those things.
It might not be what you want to hear, but nobody really knows for sure what any drug actually DOES to your brain, except for maybe some intelligence agencies or something, but if they do they're not telling us. So, for now, all anyone can go by is their own introspection and analysis of where their thoughts are going.
TLDR- 'Sall good, keep pressing on, try to stay happy. First time I got pwned by acid, I lost two nights of sleep and called my sister crying like a baby about who knows what. She called my grandma and I went over to my grandparents' place to eat, take a nap, and paint a fence for my grandfather haha.
...Point is, I reconnected with what's most important to me, and I was able to get on with my life. Food for thought, bro
Good luck, though. I really hope you can sort this nonsense out.