In Australia you can sometimes get free visits to an Exercise Physiologist under the Medicare EPS(?) scheme. Basically, your GP writes you out a referral and you can see specialist medical professionals you would otherwise not be able to afford.
Be warned though: Even though GPs legally have to do this for you if you request it some don't like the hassle of the paperwork. In some clinics there is a specific nurse that writes them out and the wait list can be a bit long but it is well worth doing. You can access someone who knows how to treat people with heart and lung issues.
It is a medicare-based scheme and you can request to be sent to someone who does not require you to pay a gap. Some physiologists charge like a $50 gap etc...but many are free and will completely bulk bill.
Some people choose to use the free visits to access psychologists or podiatrists or other specialists but Exercise physiologists are not like Physios-they take into account severe health issues like heart conditions, asthma and bone problems. They will most likely start you off very slowly and they can work out a workout routine for you that will be best suited to your current fitness level.
I hope that you can find a great GP that is willing to put you onto a really great Exercise Physio. Losing weight is hard for anyone but with IBS and heart and breathing problems? You have a lot to deal with but I am sure Excerise Physios will help if you can gain access to them. Just be certain there is no gap before you sign anything. All The Best...