advice pls

doctors don’t seem to help since it takes months to get one so i’ll ask reddit for advice, after the gym sometimes i feel extremely dizzy ( like i’m on a rocking boat ) and have bad nausea and sometimes i wake up with the same issue. i checked my glucose 10 mins after eating a banana this morning and it was 140 mg/dl so a bit high and my bp was good , but it feels like my vision is causing the nausea. i’m kinda wondering if maybe it’s diabetes since when i eat i feel somewhat better , also i can go for a week symptom free then randomly it will hit me for a couple days

if anyone has experienced this and could give me some insight on what it could be i would appreciate since this has been controlling and ruining my life for the last 8 months ( side note ive also had 5 concussions)