Do I have A mental disorder?

Ever since I had an allergic reaction two and a half years ago, I've been panicking about everything, from thinking I'm having another reaction, to hearing about a disease and thinking I have it. I sometimes feel depressed about things in my life, or I get a feeling of hopelessness. I obsess about little things, like if someone slaps my leg, I feel an urge to slap the other one to keep it "fair", or I can't summarize something without feeling like I'm leaving out an important detail. I need to know because around the time of my allergic reaction, four of my best friends told me that they didn't want to be my friend anymore, and I've just started to get new friends, so I really don't want to lose them. Is this normal for a 13 almost 14 year old?