Hello,
Don't worry,
Life threatening cardiac problem is ruled out.
It is not the bone problem.
Your pain is specific - Breathing aggravates it. Which means muscles which is attached to the ribs would have gone to acute spasm.
It could be any muscle
1.Scalene anterior
2.Pectoral is minor
3.Intercoastal muscles.
Next Steps
Just try (you tube)
a)Neck stretches (upper trapezious and scelene complex)
b) Chest (pectorals) stretch on doorway
b) Applying hit towel fermentation around the neck 10mins
Health Tips
Stop your diagnosis marathon. Try my simple advice and continue the medication which is been prescribed for 5 days. If your pain is not subsiding then meet a Physiotherapist for a detailed assessment and manual therapy.