I'm not a big fan of attributing aches and pains to detox. I'm not saying that it can't be "detox," but way to many times (imo) stuff gets written off as detox when there is an issue that should be addressed. I wasn't aware of fat giving joint pain, but if it has done it in the past, that may be the issue now. Are you relying heavily on nuts and seeds to get your calories? If so, there are some options: You could try the 80/10/10 diet, otherwards eating high (very high) fruit, a large (very large) tender green salad, and very little fat. This may work for you, it seems to have worked for many on this site. Google Dr. Douglas Graham, and you can pretty much get enough of the idea from the internet if you don't want to have to buy books.
My opinion (since you did ask) is to not write off problems as detox. And if a type of eating doesn't work for you, be willing to make advised adjustments from fellow "followers" of a plan, but don't stick with something that doesn't work after giving it a fair try. Your diet should make you feel good, not be an ideology.
The the 80/10/10 seems to work around here for many, I tried it for a couple months and found it didn't work for me. Though, I do eat MUCH more fruit now, and am much more conscious of not gorging on fats. I just never felt satisfied (how ever much fruit I ate, and I ate a ton), and not grounded (jittery may be a better nonmystical way to describe it) even though I kept my fat intake low. I recently went back to high raw (instead of 100%) with cooked brown rice and steamed veggies and that seems to work for me. I'm NOT advising you to do that, just to keep your mind open and listen to your body to see what works for it.
So sorry your joints are aching! I have suffered from joint aches as well and it can be pretty brutal. I know that certain foods can cause flare-ups. It can take awhile to figure out which though. If you are eating a lot of a certain nut you may want to switch to seeds to see how those go. Rotate things in your diet and keep a food journal/pain log. I know this sounds like a lot of work but you could save yourself a lot of pain.
As for what's detox or not, it's really hard to tell! One way to slow down detox is eat some cooked food. If you feel better, then it could have been detox. Most likely detox will end and not linger too long.
Another thought is to find a good source of Vitamin D. If I am low I can joint and/or muscle pains.