I am a 24 year old male. Before a month, I visited a hospital in my hometown for pain on the penis. They conducted VDRL and TPHA test and said that the test came back as weak positive. So, it is the first stage of syphilis. They prescribed me an injection and some tablets for five days. After 10 days, I moved to my place and got both VDRL and TPHA tests in a reputed diagnostic center and the tests came back negative. But, I have taken the medicines prescribed to me. Now, I am getting some neck pain and headache. Can that be a side effect of those medications?