Why Has My IQ Declined Over the Years?!

Why has my IQ declined? I'm already 20 years old. I was always interested in my studies, in the library and in books. Call me a nerd, but that's who I am. I write books, poetry and even poetic biographies of my friends and enemies. I took IQ tests when I was in elementary and high school which scored 130, 141, 135, 146, and so on. What I'm sure of is that the mean score was 141. When I went to college I didn't pay attention to IQ tests anymore. I still did well in my studies. After all, I was awarded with being able to take only 2 years of high school then straight to college plus the title of valedictorian, so those IQ test scores don't lie. Later on, I get out of college with an AB Humanities degree and an MA Political Economy degree (both degrees overlap where I went)-I didn't finish the Political Economy degree (just 15 units left) because my epilepsy got serious-it began when I was 9 years old but I still claimed my AB Humanities degree. I then take IQ tests online, just for fun and to have something to do while on the job hunt. I then find out that my IQ has dropped to 120, 130, even 100. Please tell me why. I did well in college. I admit I have a low EQ. I get mad easily and find myself enraged. I get into fights, but was always treasured by our school as an asset. That's why I could always buy my way out by telling the brass that they didn't want me to graduate from another university. Is that what caused my IQ's decline? Or was it something else?