What Does A Large Bruise On Inner Thigh Indicate?

I have a large bruise on my inner thigh that started out the size of a golf ball, but has spread to about five times that size (about the size of a softball) over the course of two weeks. The middle of the bruise has recently entirely healed, so there is a ring of bruising around the healthy patch of skin which has continued growing. Days before the bruise appeared, I had severe achiness in my hips and in my groin which were very sudden and again- not triggered by any sort of trauma or over exertion. I have never bruised easily and have had no accidents or recent injuries- I am a nineteen year old male in good health so this has been concerning. The bruise literally appeared overnight and was very dark purple and red, as if it was a very deep bruise, but the skin covering the bruise did not hurt in the beginning; however, overtime it has become more and more painful. Occasionally the bruise has become very cold to the touch for no apparent reason and touching the very middle of the bruise is extremely painful. My biggest fear is that it could be some sort of blood clot or blood disorder as I have felt that my blood pressure has been quite high at various points since the appearance of the bruise.