with the Lidoderm patches is that you need to do 2 things:

1) place them in the right spot for best results

2) use them for at least a week, or more.

They are not like oral drugs like opiates/aspirin etc and give relief immediately.

For my feet I place them in two places..
a) either on the top of my foot...I cut one patch in half and put one half on each foot, vertically so they cover the top area from ankle to toes (I don't need this very often), and 3 days usually will stop a major burning attack.

b) across the ankle, where the main nerve comes down from the leg, this may work for me in a day or so.

For knee pain, I put 1/2 across the back of my knee on the thigh side of the bend, this takes about 3 to 5 days.

For leg pain, I put them across my sacral area, or higher in the lumbar depending on the pain. For my thigh groin pull, I use the sacral area.
If I have pain following gardening/bending I put them higher up in the lumbar area. These take at least a week.

When I had severe meralgia parethestica I put 1/2 in the groin on the upper thigh and 1/2 on the upper side of the hip.
This was my first experience. For me, after two weeks of everyday, it actually stopped the nerve from firing like it was and now I have a 90% cure. This was unexpected. But it did teach me that putting the Lidoderm in the WRONG spot, can actually make the pain worse. Putting them on the MP pain where I felt it, did nothing but make it shoot MORE.

So time and some experimentation is needed. They work by interrupting the axon, from what I observed.