Can Bruising In The Arm Be Due To Internal Bleeding?

Hi there. I am on indomethacin for a knee injury. We went to 6 flags yesterday and after coming home, I noticed some bruising on my right arm (where the rides would have dug in or put pressure on my arm). I am afraid of internal bleeding or platelet issues.....my grandmother suffered something similar after being on motrin for years. I just want to know if this is serious. I don't have bruising anywhere else at the moment...just my right arm. Thank you!