Hi Justy,
Just to share my experience, I am having weekly HBOT sessions at my local MS therapy centre at the moment...Ive had about 12 so far this year...I had already had 2 sessions last yr a few months apart and i definitely noticed some benefits in stamina after each of those treatments, so decided to experiment with weekly sessions. The MS centres do often recommend doing a course of intensive treatments with 2-4 sessions per week and although I know that some people with ME/CFS can tolerate these intensive courses, personally I found that I can feel rough after each session, so i have just stuck with the weekly sessions and the centre that I go to were happy for me to do this.
So far I have had 4 sessions at 16.5 feet and have gradually increased to 24 feet. As I say I usually feel worse after each session but not necessarily during the session or even on the same day....usually over the following 2 days ... I think thats partly PEM from the effort of getting to the centre, but its also due to herxing - I have lyme and other infections and people with lyme and other bacterial infections are known to herx from HBOT ... since a lot of us PWME are harbouring chronic infections I would definitely advise to start at the lowest depth at first just to see if u can tolerate it. When I herx my brain gets more inflamed and I feel depressed (both typical herx symptoms for me)....but once that passes I notice that I do feel a bit better than before so that proves to me that it is a herx.
I also assume that the feeling worse might be partly due to oxidative stress. As JDJ says in her blog in regard to treating autistic children they recommend checking for glutathione first before treating as otherwise the oxygen can create too much oxidative stress (also fitting in with Cheney's ideas of oxygen toxicity)....I have low glutathione I guess like a lot of us and this might also explain why I feel worse after each session. I do take glutathione aswell as other antioxidants eg vit C, CoQ10, astaxanthin and vit E after each session....they do seem to help though i can still feel rough the next day so they dont protect against it completely.
Despite the feeling worse aspect, I have also noticed that in general I seem to have a bit more stamina and my brain has been working a bit better at times since starting the HBOT eg better concentration. However, I am pretty up and down generally and for me its really important to keep my gut/diet under control, aswell as not overdoing things physically, so that my inflammation levels dont get too high generally, otherwise everything goes belly-up and i get a lot more inflammation from the HBOT. So basically if ive been "good" with my diet, I reap the benefits of HBOT more.
Just to add like you I also tend to have low ferritin, and have been doing the vit B2/manganese like Aquariusgirl, and this seems to be enhancing iron/oxygen utilisation/metabolism in my case too. I also think that the B2 has at times decreased the oxidative stress that ive had from the HBOT, maybe because it recycles glutathione.
Hope that helps and good luck if u try it!