My 5 year old lab is nibbled my 1 year old and keeps knocking them over.

My dog has always been a super friendly and submissive dog. In the past year or two, he has become super skittish. Runs and hides when the oven makes a noise, you point at him the wrong way, or grab something suddenly. He has the uncontrollable panic and will often knock over my child because he is acting like he is running for his life. Additionally, he suddenly went up to my child the other day and did the corn on the cob type nibble and pinched my child’s arm leaving a little bruise.

I love my dog to death and I know he isn’t trying to do these things but I have to figure out how to train this out of him. Any input/advice? Thanks.