Okay --- first off it is going to take some changes to get your system to calm down. Years ago I was in a similar situation as yours. Reacting to everything...horrid acne erupting overnight continually and very infected, etc. What is making your skin itchy is that it is very inflamed right now. The pores are filled up with junk and it is infected and this causes the skin to itch. Your system is "itchy" too because of your diet and distress. It is in reactive mode.
To calm your system down try eating only whole natural foods that are also calming foods. That means no caffeine, sugars or dairy. Yes, I know this is hard to do but it is essential, believe me. Also avoid all added oils (margarine, cooking oils, fried foods, etc.) to help the gut function better. Eat things like herbal teas with non-dairy milks, salads (without dressings), steamed vegetables, whole starches like potatoes and rice, and whole flesh foods that are wild (ie wild salmon) or range-fed. Bake things, steam things, and avoid all fried foods and fast food places.
Don't worry about "probiotics". If you have a bit of undiagnosed rosacea along with your acne then eating things like yogurt and fermented foods will flare it up. Your body can naturally make its own probiotics if you eat the diet above. If you can't tolerate probiotics then it will take time but it will happen. P.S. I too can not tolerate probiotics...makes me break out every time!
You still need to kill acne bacteria to stop the itchiness but you can do it with a topical antibiotic versus an internal antibiotic. This works especially well when paired with a BP cleanser. See my regime below. I too took internal antibiotics for years and was skeptical that this would work. But it did. Took a little while to get total clearance but it happened.
Also, don't worry about Spironolactone. It is an extremely mild drug and only blocks androgen receptors. It is not a hormone itself...only controls the amount of androgens the skin receptors take up and hence it helps control acne. Spironolactone has been extensively researched and studied and is mild on the system especially in the very low doses taken to help control acne. It is 100% better than taking birth control. Don't worry if you need to take this, especially during the years your hormones are still fluctuating.
Hope this helps!