Worried, do I give my PIP up now?

Hi have not been in here for ages . Last time I received some good advice from this community.  But now I'm wondering what to do.  I have osteoarthritis in my knee and also I had large kidney stone and a frozen shoulder. I was really ill for 3 years awaiting ops couldn't claim ESA said not eligible to do with NI contributions. Didn't get a penny for 3 years . Husband took a second job as I couldn't work. I applied for pip and was awarded enhanced on mobility and standard on living this came through the day after I came out of hospital having a total knee replacement operation.  I was awarded till 2020 . I was awaiting my second OP which I had last April keyhole surgery to remove a massive kidney stone.  Now recovering from all three conditions I asked about telling pip about being in hospital  . And I was told you only need to info them if in hospital  for a long stay is this right. ?  My next reassessment is Dec . Do I give my pip up now .?  I am going back to my doctor as my other knee is now playing up and my hips cannot walk far .going to see if i can have more xrays and see if the osteoarthritis has spread . I'm worried sick what to do I'm 65 . Thank you for any advice