Bruising on arm where implant is..?

[ShadowHarts]

Has anyone had this before and know if it's normal or cause for concern?

Had my implant in a year in March. It's the 2nd one I've had and it's been fine, no issues. Today while I was jogging I noticed something in my rucksack prodded my arm a couple of times, so I adjusted the bag and carried on. Just got out of the shower and it's really bruised, looks like it's bled under the skin? It's about the size of a 20 pence piece and I don't know if will heal on its own or if I need to go to the walk in where I had it put in?

I'd get it checked just to be safe but it's such an easy thing to bruise. I once was messing around on a trampoline and caught my arm, only ever so slightly but my gosh did it hurt and it was bright red around the implant area for a good few days...