I know what you mean with the cystic acne, I had a lot of it from boob-time and on up (puberty).
Rest assured the anxiety disorder and stomach pains are related to eachother!
It's never the case that just one symptom is unrelated to another, so if you treat one, you will likely affect the other, sure as the sun shines.
I'm glad you have a good handle on the Sugar intake.
Are you living in a country that allows Genetically-Modified-Organisms crops in the food supply? You may want to halt the intake of all foods which have those problems attached. Materials such as Roundup (glycophosphate) acts like Antibiotic in the gut and can give a lot of problems.
Many folk experience relief from Acne by removing dairy from their diet, because of the bovine growth hormone added to cattle feed so they will grow faster.
The simplest tools you can currently try (and be assured many different folk will advise you to use their favorite tools, because there are many different techniques) which I have tried and enjoy consistent result on:
Drinking clay is one way to calm the gut, the emotions (because of the stress from when there's an imbalanced gut flora (candidiasis) and/or parasites), and possibly the cystic acne. Bentonite, like diatomaceous earth and activated charcoal, helps the body by adsorbing ROS (reactive oxadative species) particles before they can get into the bloodstream, and creating an environment where harmful bacteria, viruses and parasites cannot thrive.
The psyllium husk is a source of resistant fiber, which helps keep the bowels moving and nourishes helpful bacteria.