Radiation skin changes: dimpling

Hi all,

I finished radiation back in December (whole breast, 3 weeks, following lumpectomy). My skin has calmed down nicely, darker colour is fading, nipple almost matches the other. However 2 days ago I noticed a large dimple only visible when I lift my arm, in the lower part of my boob (my original scar is closer to top).

I’m very aware that this can be a symptom of a tumour which is freaking me out but can also be just be skin changes following radio. 

Would love some reassurance from others who have perhaps had a similar dimple post radio that was just skin changes and nothing sinister. 

Thanks in advance, from a chronic worrier!