Tired

I could not sleep, i had a stomackage, i feel tired, i want to sleep but i can´t i need to take a course!, so i am going to take a shower again and lets go to the university!!!,

I could not sleep, because I had a stomachache. I am tired and I want to sleep; but I can't. I have to go to class, so I am going to take a shower.

Tired

I could not sleep because I had a stomache. I feel tired and I want to sleep, but I can´t! I need to take a course, so I am going to take a shower again. Lets go to the university!!!

In english we do not use so many commas in a sentence because it creates a runon sentence. Also the word/letter 'I" is always capitalized when it is on its own.