I've been there. Benadryl(or any of its relatives) is a terrible drug to get high on. It feels like you're being poisoned and are on your way to die. What's weird is that I see too many kids acting like Benadryl is the cool thing to do.
You're 15, and most people will tell you to not do drugs. As much as you might not want to hear it, they're right, you shouldn't do drugs. At a young age like that you can negatively impact your development. You're not going to turn retarded, but you won't be as mentally stable as you would be without them. I'm a living testament to this.
If you stay on this path, you might reap things that are far from pleasant.
When I was 14, I was too stupidly eager to do drugs. I was warned about the path I'm choosing. I was given very good advice, and I should have heeded it, but I didn't. I'm an opiate addict now, and I can't stop for the life of me. No one starts out saying I'm going to be an addict or I'm going to die of a drug over dose.
If you're going to continue getting high, at least do some research first on whatever it is you're going to be using. For me,
Erowid, was the mecca of safety and information. Don't do anything before running it through the site's Plants and Drugs Index. You'll know the proper dosage, duration, action and the risks associated with the substance that you're about to do. You'll be educated instead of where you are now, making a thread on Bluelight, wondering if you have brain damage.
You also have to remember that knowledge of the drug only shields you up to a certain point. It doesn't protect you from addiction. I knew everything and anything about opiates before I tried them, that knowledge gave me a false sense of security. I seriously thought everyone around me was stupid because they're addicted and are selling their mom's TV to get high. I looked at that and thought, that'll never happen to me. Unfortunately, I didn't count on that one little part when you do something and think, "wow, this is what I've been missing all of my life. This makes me who I want to be. If God had anything better, he'd keep it for himself."
Whatever you drug of choice is, it'll the panacea of life until you're selling your mom's TV to get more of it.