Inflamed is an injury. A strained muscle might seem more like a proper injury but inflammation is possibly the tendon for the muscle and can be a bugger to shift. Worth seeing a good sports therapist or physio
I experienced exercise induced tachycardia during a half marathon a few years ago. Went through all the cardio tests afterwards, ECG obviously, echocardiogram and treadmill exercise test. Result seems to be exactly as stated a tachycardia which may have been exercise induced but also have asymptomatic right bundle branch block. Have run lots of races since and not had the same symptoms again.
As others say any number of things can cause this but always best to wait for an expert to give their view before running again. But most cardiologists will recommend exercise even for people that have a heart problem so don't give up on the fitness. Just make sure you ask for advice on what is possible for you. Also many of these things can be a one off fired by adrenaline/caffeine etc. so fingers crossed for you it is something like that.
I have recently qualified as a PT and have plenty of running experience, where do you live?
But seriously in general unless the PT is a runner, and most seem to be more into weights from what I have seen, then go to a running club. A PT will certainly be able to help with general fitness, nutrition and an overall body plan but you pay a price.
Of course some people need to be motivated and they should be able to help there but if you can't afford it then follow the advice above. You'll do well.
Also agree with most of the above, P & D schedules seem to work for most of the forumites that have used it, and weight loss of course does help but needs to be sensible for your individual body shape.
Your height/weight figures are in the healthy range but are at the top end in terms of BMI so you probably could lose a few kilos quite safely.
I would suggest looking at your diet anyway and making sure it is a healthy one, cut out the processed foods, cut back the red meats and substitute with chicken/turkey breast & fish or even have a couple of vegetarian days per week. You will find this should have an effect on your overall body fat % which should then lose overall weight but without affecting muscle mass.
You need to make sure though that during the heavy marathon schedules you take on enough carbs and protein to provide the fuel and aid recovery.