how do I know if it's a strain or a cramp...?

I was playing basketball yesterday & all of a sudden I felt a sharp pain in my right calf so that was the end of my game

I iced it & stretched it yesterday & today, & I feel pain in it when I walk (so now I'm walking by keeping my foot stiff & not bending at the ankle)

but I'm not sure if it is a strain or just some type of cramp because there was NO SWELLING

so what is it?