Sorry, this is going to be a mini-rant, but it just drives me crazy. Please read the whole thing before commenting though.
Yes, this forum is fantastic and there are many knowledgable people on here willing to offer great (and free!) advice. However:
1) Most of us have not been to school for nearly a decade to study horse health specifically. That doesn't even include the many years of experience vets have had AFTER grad school working with anything and everything that could possibly be thrown their way, as well as any additional professional development, collaboration with fellow vets, access to specific resources, etc.
2) Even vets hesitate to diagnose an animal without actually seeing it and interacting with it, though there are many minor things that my vet will work me through over the phone and especially if I can text him pictures - and guess what? It's FREE! But then again, he also knows the horse, it's history (even from before I got him), and me personally. Frankly, he knows my horse better than I do in many ways.
Now don't get me wrong, I post my concerns on here quite often (usually to find out if it's nothing or if it's something to talk to my vet about), and I encourage everyone to do so if they feel like it. Back to what I said before, there are many knowledgable and willing folks on here whom I appreciate so much. BUT, they are also the ones that usually include the phrase "call a vet" in their advice if it's necessary. Please, for the sake of your horse, take it. I know many of you do. But there are many that don't. And for those of you that don't until you think you need one (yet) or because money is tight - when you finally decide it's time to call the vet it is often too late. Your horse is likely going to suffer unnecessarily because of your hesitation AND you will likely end up paying more money to fix things that could have been prevented.
Please, call a vet.