My toilet just started last week draining the bowl and I don't know what is going on . Now I will have to check the vent pipe and the sink trap to see if it is being pulled form the sink also wow what a pain in the butt

Ya got the right idea. Unless you've dropped something in the bowl and cracked it the vent's the most likely culprit. Snake the lavatory roof vent. Put out enough snake to reach the base and 18 feet more. Good luck, Tom