It’s most likely just inflammation considering you’re suffering from this in the evening or after standing but make sure that’s not hiding something which looks more like a skin disease or an allergy (in that case, get it looked at because it might be a rare but nasty side effect of the drugs you’re taking).
Everyone is different but you’re not totally in the dark either. One thing I can tell your is that you are looking at several months during which you have a significant risk of experiencing a serious attack. By serious, I mean crawling. With enough anti-inflammatories, you might be able to stand on your feet but what you’re describing isn’t a proper attack but more like a chronic condition so it’s harder to tell how long that could last, especially without colchicine or corticosteroids. Others have suffered from something similar for quite a long time (supposedly it’s uncommon but it doesn’t seem all that rare based on what people post here).
Hopefully getting your uric acid very low might put a stop to it sooner. So if it hasn’t stopped after a few more days, I’d try 60mg or more. I’m not sure more than 60mg would help but given your test results, sticking to 40mg for a while is only worth doing if that keeps the symptoms at bay somewhat. But if you feel 40mg is as bad as 80mg, staying on the lower dose is only going to make your recovery slower.