I was told Wookie

had luxating patella when he was little (he is 3 and half now), but it wasn't bad. Just something to keep an eye on. It just popped occasionally at that point. Well, last Oct he had to have emergency exploratory surgery in his intestines and when he got home from the hospital I noticed him doing that lifting his back leg and hopping around for a few seconds then be fine thing. Took him to the vet and she said that the surgery aggravated his luxating petalla because of how they have to tie down his legs for so long. She thought it would be ok, just keep an eye on it and we went ahead and put him on GlycoFlex. She said he could possibly get worse and eventually need surgery, or it could not ever get that bad. We just have to watch it. After a short episode of doing the leg sticking thing, he quit doing it completely. Has only done it one other time since then, when he got his leg caught up in some weeds in the back yard. Then he only did it for a day or two. Well, 2 weeks ago, I was taking something away from him that I didn't realize was tangled on his back leg and when I pulled it away from him he yelped and limped around for a bit. The rest of that day he was real ginger on it, but then he was ok. Now he is doing that leg catching thing again, a lot. It has been 2 weeks now and it doesn't seem to get better. It pops out just when we play around in the floor.
Was wondering who has experience with this? I wonder if this is just an aggravation from that day that is lingering or if there is more damage. I don't really want to go to the vet and pay for a visit if she is just gonna tell me to keep an eye on it again(I lost my job 2 months ago and money is really tight right now). I will if I need to though, if there is anything more they can do for him. I am just soooo scared he is gonna need surgery sometime....