Pain in the right thigh, walking problem

Hi, My sister is 43 years old and she has infantile hemiparesis and varicose veins. She is on medication( Lacoset and Eptoin) which controls her seizures. Her varicose veins is also under control due to regular oil massages and elevation. Since last week, she has been experiencing pain on her right thigh and is finding it difficult to walk or sit. Although, there are no marks of any injury, I am unable to figure out the reason of the same. She does sleep on her right side dominantly. I have been giving her combiflam for pain relief and the pain has subsided but not entirely. Due to her medical condition, she always has her left leg stronger than the right, but never before had she experienced such pain. Please advise.