Swollen And Itchy Shin, Looked Squishy And Painful, Bruise On Shin Spreading. Solution?

Hello and thank you in advance. I am curious about something unusual that has happened on my right shin . A little background: I m a very active, healthy, non- smoking female. I have a 13 month old daughter, who I carry often. I had a strange pain and itch on my shin the other night. When I looked, it appeared as if a vein was raised and slightly bumpy. It looked squishy and it was painful to the touch. It had an itch/allergic reaction sensation to it. I was not bit by anything. It happened at night, somewhat out of the blue. The swelling is gone and the pain is also gone but there appears to be a bruise now which has spread and grown in size. I haven t bumped my shin. I am perplexed.