What was the name of that movie?

Iv been searching for this movie for a long time. I Only have veg memory's of it i hope someone can finally help complete this quest for the name of this movie lol. here is goes. I now its about this young boy who see's something that scares the heck out of him & all his hair ends up falling out. then he ends up getting this potion that i remember looking like peanut er that someone told him to use on his head to grow hair back but ends up working a bit to good and his hair keeps growing . don't remember what happen after that but i now the main bad guy of the movie ends up finding out that the boys hair became magical some how and when you use his hair as a paintbrush you were able to walk into the paintings. (gasp) i cant remember anything after that besides one scene when the young boy and his friends were looking for one of there Buddy's they come across a painting the baddguy painted of a snowy mountainside with footprint in the snow leading into the distance so the boy and one of his friends go into the paint to go after there buddy. i think one of the young boys friends was data from gooniese . this move came out in the early to mid 80's