I had tests done to find out which foods I am sensitive to/intolerant of. Dairy, Gluten and Eggs topped the charts for me and are basically full blown allergies, although I am not considered a celiac.
About a year ago I travelled to Nepal to do some volunteer work there, and unfortunately I was in situations where I could not control my diet and was ingesting quite a large amount of foods containing gluten, eggs and some dairy. Low and behold I had the worst break out of my life, and not just normal acne, but crazy inflamed cystic acne, quite possibly similar to what you are talking about, only mine would develop a head eventually with pus and all that jazz.
When I came home from Nepal, I put myself on an incredibly strict diet, I am now a Gluten-Free Vegan basically, and my skin completely cleared, although it did take some time, and I will get a pimple here and there...but nothing compared to the craziness of what happened to me in Nepal. I know for a fact what I eat is directly connected to my break outs, especially the horrible cystic ones.
I really wish Doctors would look at diet more instead of just laughing it off...so many people could be saved from the misery of acne if they started to consider their diet (although I know this isn't true for everyone, and for a lot of us, it's a combination of many different factors)...but diet can no longer be ignored.
Although I am cleared, I unfortunately have a face full of pretty horrendous scars because of three months where I could not control what I ate.
Cystic acne is pretty unforgiving in that not only does it hurt like hell when you have it, but it also leaves it's mark...permanently.
It's interesting to me that you are getting cysts/nodules from oranges/citrus fruits. Have you every considered taking an allergy/food sensitivities test?