Clock Skew Problem

Note that it doesn' t have to be 1 pulse signal. Just chane the if condition to:

if (counter[6] == 1'b1) begin

It will now be low for 64 clocks, high for 64 clocks, etc. And as mentioned, it should not be part of your sensitivity list, just part of the synchronous logic after the clock.

The coding is generally pretty straightforward, but the timing analysis gets difficult. Note that everything will be timed to the clock rate, which is too fast. I believe there are posts on this board and the website about use get_fanouts, which is what you'll want in your .sdc file.