Car engine issue?

hi guys, I’m going to try to not make this too long but I’m just looking for any tips or thoughts on an issue im having.

my car has been jolting and flashing the engine light about 5 times and then stopping when I accelerate for a few weeks, I had my spark plugs replaced and the issue seemed to get better the past two days, yesterday when driving it was only able to go able 70kms in a 110 and the engine light would not stop flashing at all which I’ve heard is really bad, it ended up getting slower and slower until I had to pull off to the side and by the time i had put it in park it was vibrating and jolting so badly. I had it towed home and the guy said there’s no engine light on and it drives fine? I am just so lost here and it was a really dangerous situation so don’t want to risk driving on a motorway again, but also financially in a tough spot to try to get it into a mechanic without knowing how much I am in for. anyone else had anything like this or maybe know what it could be?

any info would be helpful/appreciated

thank you