Sorry to hear about your rejection letter...it's a rough job market out there unfortunately. I work in HR so hopefully I can give you a different perspective on helping to bridge some of the gaps on your work history.

First, realize that a lot of people are going to have a spotty job history in the past couple of years in the job market. With that being said, there are surely things that you have done during the times you were not employed for pay--focused on being a full-time homemaker? Volunteering? Helping older relatives? Perhaps all of those? I would definitely use those to fill in the gaps; the majority of HR people are relatively narrow-minded and think that everyone has to do "something".

As far as mentioning illness of any kind, I would personally avoid it. The law does not require you to disclose it during the interview process--the only time you would need to disclose a limitation would be post-offer for a reasonable accommodation. An example of this might be if you needed an extra break in the day to get up and walk around due to restrictions on extended sitting due to back problems. If the company you are interviewing with asks outright if you were ill during those times you were not working, this is not a legal interview question and is a violation of HIPAA laws. Of course, with jobs as scarce as they are, the diplomatic thing to do is to smile and talk about volunteer work

It's depressing to me as an HR professional that there is still such a stigma about hiring individuals who are working through a physical or psychological recovery. I personally do this training (on mental health awareness) frequently at work and at my HR-related trade organizations, so I'm thinking there might be hope yet.

I wish you the best of luck in finding a good job, and if you want any help with interview questions, interview prep, resume...etc., just PM me.