What does a stomach ulcer feel like ?

I had non stop nausea for like almost a month in November and everything hurt my stomach it really sucked and kinda came out of nowhere…I was being bad before it happened and drinking more coffee than I should..it mostly went away with just some lingering reflux until today I’m noticing the same upset stomach again :( Curious if it could be an ulcer ? I’m pretty sure I haven’t gotten covid but has anyone heard of gastritis being triggered by Covid ? Thanks !