Can't really say what's normal, but I did have 2 months from my last FOLFOX infusion 12/13/17 and starting FOLFIRI + Avastin on 02/14/18 (Valentines Day and Anniversary and made it through dinner fine). I had a post chemo CT scan with results on 12/28/17 which got me to a liver biopsy and 2nd opinion scheduled in Jan. which took some time.
I do not have a stoma so I can't offer any thoughts on that, but I had my 3rd FOLFIRI + Avastin today which they have been giving me an atropine injection each cycle to help. So far I've only had one case of diarrhea on Day 1 of the first 2 cycles (none today) and took 1 Imodium each time with no more issues. As far as hair loss, I lost some hair during FOLFOX, but seem to be losing more on FOLFIRI (went ahead and shaved the beard do to loose hairs). Top of head was thin before chemo, but sides and back still hanging in though thinning.
Unfortunately, the side affects just like our cancers, vary with each individual. They do share several commonalities and some of the longer term members can probably give you a better take. Good luck to your mum and you!
56yo male DX 5/17, Right Hemi colectomy 6/17
Stage 3c 12 of 21 LN
7/17-12/17 Folfox(no Oxi round 9-12)
12/17 liver/lung mets-Stage 4 MSS KRAS G13D
2/18 liver doubled to 8.5cm+new met, lung mets to 1.4cm, multi peri/omen
2/18-7/18 Folfiri+Avastin(no 5FU after C2)
4/18 mets shrinking
7/18 liver/lung mets growing, Folfiri stopped
10/18 In Clinical Trial
CEA 5/17-16.2, 12/17-16.1, 02/18-43.0, 3/18-16.9, 4/18-9.0, 5/18-5.5, 6/18-6.9, 7/18-7.8, 9/18-56