Hi
Sorry to hear that you are suffering. It really is a horrible, painful condition.
I was also diagnosed last year and thought (perhaps foolishly) that it would go away and was only temporary.
I now have symptoms regularly and like you the pain began and still occurs across my chest and often along the breastbone but also recently in my back which is horrendous!
It is common, I was told by my GP that people who get it think they are having a heart attack and go straight to hospital which I felt was a good indicator of just how distressing it can be and how seriously painful it is!
I had to give up working where I was as it was a stressful job but the job I have now is a little better but still causes considerable problems for me. Any lifting/ stretching etc can and will trigger it which makes daily activity really impossible because any 'exercise/activity' that pulls or stretches the muscles around the ribcage or chest in any way can and will just amplify the symptoms to such a point I become immobilised in pain.
I was also later diagnosed with fibromyalgia and IBS (which I believe from my symptoms I had had for at least 5 years before diagnoses! That's another story.) and this was on top of my existing osteoarthritis in both knees, my neck and my right shoulder (triggered by a bad car accident) and diverticular disease.
Anyway, anti inflammatories are ok short term but I believe that my tummy problems may have been caused by taking naproxen, ibuprofen etc. so you are right to be cautious.
I have needed to swap around my thinking and look very very carefully at my diet and nutrition. I now have cut sugar (a natural inflammation-causing substance) and increased incorporating anti-inflammatory foods into my diet (lemon juice, turmeric, apple cider vinegar, low sugar veggies and fruit (berries). I believe this has helped me a little although I'm far from finished with the diet modification angle. Here's a link to website that has helped me find out the basics of anti inflammatory foods:
https://draxe.com/anti-inflammatory-foods/
Also Check out Dr. Myhill's website: http://www.drmyhill.co.uk/ who deals a lot with chronic conditions with considerable success but her methods are totally uncompromising as arguably so is the diseases she treats! ME fibromyalgia, etc.
My stepmother has had the condition for years and there are two things she has found helpful which I can share in the hope it will help you.
Regularly gentle swimming (I mean gentle) followed by (and this is vitally important) a sauna, in fact there is no such thing as too many saunas where costochondritis is concerned as it fully relaxes the muscles, tendons etc. and should help with stress relief which is all good!
Both aquatic therapy and saunas have also been tested by some of the medical profession to significantly improve things for sufferers so that's worth knowing.
Also she got a clever friend of hers to make her a bespoke elasticated kind of corset thing which is a bit more substantial than the back support belts etc. you can buy as it covers the body from her waist to just under her breast bone but because it holds the upper body in one position it seems to have a really positive impact for her. I am currently considering this myself but it may take some making!
My New years resolution is to have more saunas, lots more saunas and lots more hot baths and showers.
I know it's tricky to feel any hope or motivation to push past the incredible level of relentless pain you are in so on those days just stop, wrap up really warm (preferably thermals) if it's helpful and just be kind to yourself, let yourself off the hook and I really really hope you feel a lot better very soon.
Kind regards
G.