Hello.
The problem seems to be due to soft tissue strain in distal thigh and leg muscles.
It may happen due to the Injury you had when had a fall leading to localized fibrosis.
Yes, sometimes over exertion may also cause this.
It doesn't look any side effect of medicine
Next Steps
You can start with hot fomentation, take analgesic with muscle relaxant tablet,
calcium and vit d supplement, apply analgesic ointment for pain relief.
Health Tips
You can also start with some Physiotherapy like SWD, Local US that will help in relieving the symptoms.