i noticed on my guinea pigs foot this hard black thing, i googled it and all that was coming up was spur but this looks bigger than the other pics i have come across and getting really worried now, i am trying to add a pic but not sure how to, if anyone can tell me how to do this then i can put a pic on, sorry if i am sounding thick i am new on here and just want to see if it is anything to be really concerned about, thanks in advance x