Disclosure: I am not a medical doctor.

Your symptoms are exactly like mine. I am impressed that you were able to write that much about it before you got distracted. I like to explain it like this; My mind is like a tree. One loud central thought sprouts 4 thoughts which sprout 4 other thoughts, and so on. As the tree gets thicker the limbs begin to cross. Birds build nests, the wind blows them all around. Before you know it, you went from changing your shirt to "the actual color of the blue footed booby's blue feet" (in like .0002 seconds). It's very exhausting.
Talk to a doctor about medications. There might be something you can try that will be better for you.

not a doctor myself.

tested positive for ADD very early in life, went to a private school that was the only one in the area that had a program for dyslexic students, where they pinpointed ADD very fast due to the high concentration levels required for some of the courses. took Ritalin as a kid and was on it till high school. got a new doctor who put me on more than 4 times the dosage i had been taking, at that point i told him to bugger off and stopped taking all meds.

did surprisingly well after i got used to how i reacted off the meds. had to put a lot more effort into remembering things, i had to make notes in things like my binders for classes or at worst a post it note. eventually i was able to pay attention for 30 minute sections of time without getting too distracted, hit my college years and enjoyed the fact my classes lasted 50 minutes then i had time between classes to think a little. got a bit hectic when i started taking a lot of classes in all subjects and keeping my mind on one became almost impossible. didn't do much homework because of it but i picked up subjects very well in theory.

biggest toll i had from this was not being able to sleep because my mind would never stop. i would go 2-4 days without sleep at a time because i was unable to fall asleep. got to point of hallucinations from sleep deprivation. got on sleeping pills for a long time to correct sleep habits, the pills themselves never set a sleep pattern for me but it did get me to sleep. i learned tricks to help me fall asleep over time and rarely have to take sleeping pills any more. one of those tricks is to pick a book to read that's not terribly complex or all that interesting. force yourself to keep reading it to not get off track, this helps me keep my mind on one thing long enough to get me tired and lead to sleep.

aside from sleeping habits being off i cope very well for not taking any meds for my ADD that become more under control every day for me. things that help me train my mind to stay on task is doing things i enjoy, that are very simple, but do require concentration. for me math has always been a subject i was good at but did not always like, i like it a great deal more now and if i need something to think about i pick a pretty difficult problem and do everything i can to solve it in my head without writing anything down.

but i do recommend seeing a doctor, when it is bad getting it under control is important as it can be very draining physically and mentally. it is important to seek help when you need it, a doctor can offer many forms of treatment. all i have is a bit of personal experience and how i have dealt so far.