How do i get rid of old mosquito bits that left dark spots?

Coco butter : These dots you mention are most likely superficial scars. Depending on how old and how deep they are, most fade away with time . Coco butter has been a favorite skin treatment by many but no promises can be made. See your doctor for a full skin exam and further treatment recommendations. Use big repellant + sun screen, stay in during dusk or dawn(peak bug activity) don't scratch new bites.