Probably the nerves supplying your lower feet are getting compressed in the spinal cord
in the region of fluid collection. That is why you are getting the pins and needle sensation. One of the options for the treatment is surgical decompression of that region so that fluid is removed and it no longer presses and irritates the nerves. Some medications are also available which reduce such kind of tingling
, but they wont tackle the primary problem i.e. fluid collection. You should see a neurosurgeon/ spine surgeon
and he will guide you about further treatment.