I went paintballing 3 days ago. i had a small bruise on my arm. this dark mark is getting bigger by the day, this morning i realised that it is covering half of my upper arm. should i be worried? and what can i apply? it is painful when touched?

Hematoma: You have bleeding under the skin from paintball trauma. May need mild compression and Tylenol for pain, not aspirin or ibuprofen as they may further bleeding. Consider Arnica Gel or ointment applied topically to help accelerate fading of bruising. Monitor size of bruise and if it keeps growing much more or skin breaks down get examined.