What can be a patchy marks from the base of the hair, on the face and spots on the chest.

Recommendation : Not sure that patchy mark on scalp and face the same that on the chest. Need to see these. But patchy marks on chest at your age most likely tinea versicolor that often happens at hot weather with a lot of sweating. It could be successfully treated with special shampooing. You need to see a doctor for prescription. And keep yourself dry.