HelloI used to have this problem, is it your big toe that is hurting?You say your shoes fit perfectly but I beg to differThis happened to me and other people I know because their shoes are slightly too big, meaning every time you lunge your foot moves inside the shoe and your big toe hits against your shoe, the blood underneath the toe has most likely dried by now meaning your toe nail will possibly fall off, when it does make sure to disinfect your toe really well as you don't want it to get infected, then I would see about getting a new pair of shoes half a size smaller if that's the issue
Make sure that your shoe is tied well and properly tight so that your feet won't move in your shoe so much,your feet will always move in a shoe as fabric stretches after wear, however if your shoe is slightly too large then there is more movement, this means you'll get a larger impact when your foot moves, what you have is called RUNNERS TOE
yes, BE CAREFUL. This didn't really happen to me until I bought Head shoes (the ones I have now). During singles, I must have lunged too much during a tournament because I began to notice a large amount of blood store underneath the toenail. Eleven weeks and two days later, the toenail is coming off soon (it is loose), and research has told me that 18 months is the standard growing time for the big toenail. it is probably not a footwork problem, especially because I have trained my footwork extensively for the past 20 months, and it didn't happen until eleven weeks ago. My shoes are Head Speed Pro Lite 2, squash shoes. They are significantly heavier than most badminton shoes, weighing over a pound each. These shoes probably aren't a problem for squash players because of their different set of footwork, but I can confidently say that I will never buy shoes online again, because I thought that BOTH shoes totaled at just over a pound, not EACH shoe. Stick with badminton shoes, and to physical stores, as much as you can.