Cat limping putting slight pressure on leg

I woke up and my 12 year old cat is noticably limping but is walking on the hurt leg, though not putting full pressure on it. She is able to jump and climb up stairs, doing this on her own will, but when she does her leg shakes.  I am not sure if it just hurts or if it could be something more, would she act normal otherwise if it was broken/sprained? 

I never had a cat had this happen so im not sure if she needs to be seen by a vet or if she may have jumped the wrong way and hurt it but not less than when we get a small bruise.

Since you don't know if it's an injury or caused by an illness, I would take her to the vet, especially since she's 12.

My cat did once sprain a paw because she loved to sprint down the stairs and take a flying leap and land on the hardwood and go skidding. My husband saw her land weirdly once and she started limping a little. We called the vet who said it was most likely a minor sprain but to bring her in if it didn't seem to get better within a week. Luckily, she was fine in a few days.

I'm concerned about the leg shaking. That sounds more serious than a sprain to me.

We brought her in. No break, the vet said near the knee was slightly angled most likely sprain or muscle tear and it just needs to heal on its own. They prescribed metacam 1.5 mg/ml oral suspension, for 3 days to rid the pain. Our cat has never had pain killers before, so I am not sure what to watch out for with side effects? If she isn't better in 3 days they suggest an x ray but I'm pretty sure it's just pain that will go away on its own.

Glad to hear it wasn't more serious. Metacam I believe is one of the pain meds that can have some serious side effects. I don't have any personal experience but search Metacam here, and you will see various member experiences.