Hi Anthony,
I’d agree with the previous reply. It is quite possible your problems are due to an infection, and there is a tiny chance it could be due to an allergy, particularly if the bone graft was derived from bovine material. You shouldn’t have had these symptoms for three weeks and your surgeon may need to remove the graft. Once the area has healed then you can almost certainly have another bone graft so you will still be able to have your dental implant.