I am 12 weeks off of a total hip replacement and off crutches a week now. I woke up this morning and both my ankles and legs, below my knee, were very swollen and redwith white bite like spots. Any guesses what it could be?

Concerning. If you were on crutches for 11 weeks after a tha, that suggests that there may have been problems early. The swelling in both legs reflects poor venous return. You should be evaluated.
Probably unrelated. 3 months post-op without previous problems means current symptoms likely unrelated to hip replacement. Blood clot or DVT 3 months after hip replacement is unheard of, and would not involve both legs. The fact that this rash affects both legs suggests that the hip replacement is likely unrelated.
See doctor or go ER. This could be blood clots. You need to see your orthopedic asap or go to er.