Hallo NicolaAnne,
Sciatica is terrible and strange pain!
Had it as a teenager and did 'A' levels standing up in Biology Lab, because sitting for too long caused me to faint with the pain.
At 50 had an operation as pain unbearable. Now lots more problems with back (at 61) as lost much sensation in one foot and leg, finding going upstairs hard as is walking on uneven ground. Very worried about future mobility. Limping quite badly.
there are things you can do -exercises, etc, but first you must get properly diagnosed. It does sound like sciatica, but it's vitally important to have scans/x-rays to ensure it's discs causing problems with the nerve.
Once it's diagnosed you can look at ways of improving things and learning to relax a bit.
Let us know how you go on, but I really emphasise you need to get this diagnosed. I live in France where tests are prescribed quickly.
Jane.