Hey brother. I've been there several times while running a sheiko format. One good thing is that the maximal strength gains you have lost can be recovered rather quickly when coming off an illness(although never fast enough imo) What I have learned works, for me at least, is to look back 3 weeks in your log. Perform a ramp up set to your final working set rep range, (on the competition movements)and go for rep max. Using this number calculate an estimated one rep max and subtract 10%. This allows for the decrease in overall work capacity. The next week subtract 5%, and then the 3rd week should be full workload at your given max. This has typically allowed my strength to return, or at least close to, my numbers preillness. If you are determined to stick to a sheiko routine, it may be something to keep in mind. Again, I have determined that this seems to be what works best for ME. Good luck brother.
