Why do my bruises change color?

I know this might be a silly question but it is bothering me. I don't metabolize coumadin (Warfarin) so I take an Imitrex injection daily. The other morning the bruising on my abdomen were a greenish and yellow color as if they are healing. That night they were all a dark purple color and remain that way. Why would this be?

[Hidden]

So, the bleeding would cause them all to go back to purple? I have a doctor's appointment with my blood doctor next week. Thanks! Just didn't know if this was common.

[Murphy0866]

I was told to note the size of the bruised area and if it continues to get larger there is need to have it checked

[emmaj]

I had a big bruise that went very purple and a bit painful on my calf, i was told it was a heamotoma, which i think is a bit of bleeding under the surface,and nothing to worry about. I used to get large purple bruises when i injected and a nurse once told me i may just have hit a blood vessel,again nothing to worry about, but if it does get larger then just get it checked out x