Painful 4-5 red sores on roof of mouth (internal) and some white lesions, tip of tongue has white blister. Fever for 3 days. Due to kissing? Pls help

HSV-1. You may acquired the HSV-1 infection, that is the same virus responsible for cold sores. When the virus causes apthous ulcers, they can be very annoying as you well know. See the Dr. for a definitive diagnosis as there are oral pain medications and anti-virals that can help you. Best wishes.
Possible Coxsackie. This could also be Coxsackie virus, a common summer viral infection that causes the symptoms you have. It is most common in children, but adults can also get it. The treatment is ibuprofen and plenty to drink, so that you don't get dehydrated. The virus generally gets better after 5-7 days.