If you are considering to have tattoos on your foot, I suggest you to think twice for its pain you are going to deal with. The foot tattoo pain usually stands for more or less ten days. However, if you are the true tattoo lover, I believe that the foot tattoo pain you will have is just like an enjoyable sensation. So, it totally depends on you whether you will still stick with your plan of the foot tattoos or just retreat.
For your information and safety; it is better for you to wait the previous foot tattoo you have had totally dried before planning to add another one. Having two or more tattoos at the same time might cause you big problem to your own healthy. I do really suggest you to let the foot tattoo pain relieves by itself without any cure or medicine.
However, if you are unable to stand with the wound, you may try a painkiller. Make sure that you only use the best one unless it will just give another problem like side-effect. Actually, the painkiller itself will not help you much. It will just cure your foot pain temporarily before the wound finally comes again.