What Are The Side Effects Of Penicillin Vk Tablets 250 Mg Dosage?

i have been taking Penicillin vk tabs 250ml since last Sunday for Toncilitis i have a very sore mouth and can not eat hardly anything.i went back to my Doc on Wednesday and was told to continue on the Penicillin,my mouth is the same with sore Palate and ulcers on my tongue,am so fed up of this pain in my mouth .any help would be apreciated.......