Sorry to hear that you are going through such a bad time
Syphillis is very uncommon in this day and age (around 700 ppl in the UK contracted in last year), so am so sorry to hear that your hubby may have it. I hope that you find that it is something else as I am totally sure that this infection has symptoms (as someone above mentioned) however wishing you the best of luck and hope that all your results come back so that you can both take the appropriate medication and get sorted :-)
However if you have any further questions go to google and put in NHS Direct and then type in syphilis, it has tons of information on there and is really helpful. I tried to copy the link but my PC wasnt having any of it !!
D xx