Sorry to hear about those side effects. They sound awful.
I’ve been on 1g Valaciclovir for almost a year (plus 900mg valcyte). I haven’t lost weight, but I find it impossible to put on weight and am also already underweight. I sporadically have nausea and stomach pains, but haven’t noticed a change in frequency related to the antivirals. My main side effect from valaciclovir was the first two months when I was on 3g per day - poisoned feeling, stabbing pain in underarms and nerve pain in hands and feet. Hence I dropped back to 1g. Not sure how helpful my comment is, but I just wanted you to know I considered it and can confirm no (n=1).
Also re dropping your dose to 1g every second day - my doctor said when I revised my dose down to reduce side effects, that the best dose is the maximum dose that you can consistently take to keep antivirals in your system. I was taking 1g 3x per day. Dropped it to 500mg twice per day and have kept that dose for 9 months. Perhaps you could take 500mg daily rather than 1g every 2 days to keep some drugs in your system? Of course I don’t mean this to be medical advice and please feel free to ignore, especially if your doctor said otherwise. Just an idea.
Take care.