There are several possible reasons for a snake to suddenly stop feeding. The two most common ones are stress and improper temperature. But in your case, the frequent shedding thing and the earlier health problems suggest that there could be more to it. And, as posted earlier, sometimes they just slow down in their feeding during late summer.
I'm having a similar problem with my Texas Rat snake, but it's only in the early stages. Normally a voracious eater, she hasn't fed in nearly two weeks. Here's what I'm doing: First, minimize any potential stress. After a thorough cage cleaning (new substrate, fresh, water, etc.), I'm leaving her alone - no handling for a while - and placing a temporary cover (towel) over her enclosure to give her some added privacy. Second, I'm monitoring the temperature of the enclosure closely, and using a heating pad to maintain a temperature of around 85F in the warm end. The cool end is kept at room temperature, 70-75F. By maintaining a temperature gradient, she should be able to find a spot that's just right. Temperature is important, because if it's too warm or (especially) too cool, she won't be able to digest properly, in which case she'd probably regurgitate even if she did eat.
They can go quite a while without eating. One month is not a cause for big concern, but if it gets closer to, say, two months, it's probably time to start getting more concerned.
I hope this helps.
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MichaelB