My supply seems to do this after 6 weeks too and my babies have all been unsettled. This is the first time I have persisted through it and I am still feeding and 4 and a half months (that is a milestone for me). My supply seems to now be sufficient for my baby's needs. This has never happened before (possibly because I gave up too early previously, but I don't know).

I read a lot of of stuff on the ABA website about increasing my supply - http://www.breastfeeding.asn.au/bfinfo/supply.html - this article helped me immensly.

Good luck with everything ...