Red purple bruises, soreness, bulging vein on the inner elbow post a fall. Taking Pradaxa for blood thinning. Is this thrombosis?

I m on Pradaxa, a new strong blood thinner. I was going down the stairs, slipped, and my 130kilo body started down, I hooked my right arm at the inner elbow around the square (sharp) bannister pillar, and thus my ass was fine, but later in about 12 hours my right forearm (had shown red and sore) for about 20cm below the inner elbow got red purple blue bruised and sore. More worrisome, the vein started buldging out (at the inner elbow and about 5-8cm above), the new buldge about 1-2 cm high - never happened before and the red/blue bruising is there and looks awful. It s now been 5 days and it s still sore and there. Could this be thrombosed, and do I need a doppler, whatever that is?