He ate it around 3:30 (been around 7 hours now) and was completely fine after, running up and down and playing with my other dog, then he went for a nap and around 5 he just started crying, at first we thought he might of pulled a muscle since he had a bad habit of jumping up and down on the couch and since then he hasnt been himself.
If he doesnt get better by tomorrow my dad will definitely take to to the vets, we were going to take him today but my dad got home from work to late so we couldnt
Edit: He really didnt eat much cake at all, it was just a few crumbs and no icing or anything like that, i know it was stupid of me to leave the bowl on the couch and i have learnt my lesson