Symptoms are not used to diagnose HIV, they are seldom helpful in any conclusion because these symptoms are such generic in nature that it can occur due to several other ailments. Also, your symptoms don't seem to be specific to HIV ARS.
If you feel you have somehow exposed your self to the virus, you can get tested at 28 days with a IV Generation HIV test. I personally feel your risk is somehow low if not lowest because you seem to be from a lesser HIV prevalent demography and unless you shared needles with people who inject drugs I wouldn't see a reason for you fret about it.
Most likely your ex didn't give you HIV. Because he'd have had to had HIV himself. That's pretty unlikely. HIV is actually hard to transmit as it is a fragile virus. Air and saliva inactivate it. There is less than 2% transmission risk from an episode of unprotected sex. However, since you suspect he cheated, you are now out of the relationship, I'd go ahead and do exactly as Mike_no says and get tested at 28 days past the last time you had sex with him. Then you can move on.
Symptoms are not reliable and not used to determine if someone has HIV. Only tests. So, get your clean HIV test and then see a doctor for why you aren't feeling well.