Unless you are in serious pain, or unable to use that leg, I think that an ER visit would not gain much - just a suggestion to visit your doc tomorrow. Weekends, especially in summer, ERs tend to be filled with trauma and accident victims in most places...
PT is Physical Therapy in the US, or physiotherapy in most of the rest of the English-speaking world. It is an evaluation of your need for stretching, exercise or hands-on therapy by a specially trained therapist. Unless something is broken or torn, this is most likely what the doc will suggest.
In my experience, you will be given series of exercises and stretches to do at home, with periodic returns to PT to check your progress and add more as you progress. It is VERY important to do the work at home - as instructed and as often as recommended - without pushing too fast and causing more issues.
Good luck tomorrow
Sue