Welcome to the forum adam, it looks like keratosis pilaris to me which is quite common on arms and thigh. Check if your parents have them?
Although harmless condition it can sometime be annoying. Does it itch? applying moisturizers along with peeling agents like (retinoids, salicylic acid, 15-20% urea, lactic acid) and mild steroids might help resolve the lesions. But there is no any universally accepted effective treatment for KP. Please visit the dermatologist and confirm the case and he/she will help u with the best medications.