I guess 'the spiel' is about covering all possible scenarios & side effects. What she perhaps didn't communicate effectively was that everyone reacts differently to Radiation so you may or may not experience these side effects & they are cumulative rather than instant.
I had surgery & Radiation 13mths ago (about to have it again for other breast) & didn't experience any side affects until the end of week 3 (severe itch & a bit of fatigue). I have a friend who has had a double mastectomy, chemo & is currently undergoing Radiation & she started experiencing side effects at the start of week 2 (burning, fatigue).
Hope your subsequent sessions are less stressful!
Mel xxx