I Have An Infected Toe Due To Losing A Toenail.

i have an infected toe due to losing a toenail. I have already taken a course of amoxci[an but my toe is no better. My podiatrist had recommended Flucloxacillin so I told my Dr and he has now put me on a two week course of Flucloxacillin 500mg 4 times a day. When reading the information leaflet that came with the tablets it said the usual dose was 250mg four times a day. I am 61 years old and there is a warning about taking this if you are over 50.
Is it safe for me to take this and is it ok to take such a high dose?