Just move on if you don't want to read health stuff...
I've had some pain in my left hip for several weeks, but nothing too drastic.  I assumed it was probably the sciatica returning, but it wasn't too painful. 
Then we took Oswin to the Winchester Science Museum one day during half term.... the long car journey set off serios pain in my leg.
The next day, Friday, I was still I pain. Probably nothing except my pre-booked Covid booster would have got me out of the house...
The pain was so bad that I couldn't sit down in the chemists, just keep walking in small circles.
By the time I got home, I was I  agony.
Of course, the physiotherapy is closed on Saturday and Sunday...
I managed to get an appointment on Tuesday, and had to lie down on the back seat of the car to get there. Sitting on the seat was more pain than I could handle.
The physio, who has been treating me for many years, surprised me by saying that he thinks it is bursitis in my hip on this occasion, rather than the usual sciatica.
Saw a doctor yesterday, who thinks it is sciatica..
The two can have fairly a similar symptoms. 
On the whole, I trust Manfred - it's his area of expertise.
But if it is bursitis, then I'll need a doctor to recognise as such in order to get treatment...
On the plus side, Manfred says rest will help He thinks the long car journey caused the inflammation.
I just wish it would sort itself out quicker... I'm doing an awful lot of lying down with an awful lot of painkillers at present.
About the only useful thing I can do is to teach English to a couple of Ukrainian friends.