This could be acne, allergic reaction to some substance, eczema or even herpes labialis.
It would be best to drink plenty of water, apply a medicated lip balm with sunscreen and replace any deficient minerals and vitamins in your diet.
You could take some oral antihistamine medications lie cetrizine or loratadine and see if it helps with your symptoms.
If your symptoms still persist after a few days , it would be advisable to consult your doctor and let him/her have a look at the lesions.
Have you had allergic reactions in the past? Are you allergic to any specific substances?
Let us know if you need any other information.