You need to call your vet for advice. Many OTC meds can be safe for animal use, BUT they are in the wrong doses, or combined with things that animals react badly to. Your vet can give you some quick advice over the phone.
One thing you can try is buying a drummel. It is a little easier for a lot of dogs than clipping. Also, if you haven't tried it, take dog to pet salon or vet to get clipped. Sometimes they are easier for strangers to handle.