Yes, melasma is a disease which gets worse in sunlight. You need to cover the rest of the face with a mask or cloth in addition to the helmet and also use a good sunscreen.
Oiliness of the face is due to many reasons - hormone related, food related, due to external applications, seasonal, etc. You should use a good facewash which gently cleanses your face.
Since you have these skin problems, you should go for dermatological products specific to your skin type.
For a detailed treatment plan, you can consult me online on Practo or visit a nearby certified dermatologist.
Next Steps
Consult a certified dermatologist.
Health Tips
Do not self-medicate.