I have the same problem now. For almost 3 months I am wearing
Phallosan for approx 10 hours per day. Most of the time without the cap. Now I tried the cap since I changed from the large bell to the XL bell and had more space. With the cap I had no stiffening of the glans and no problems with the frenulum anymore. Unfortunately the cap broke after 7 days of use. I don't think it makes sense to order a new set of caps from
Phallosan. Larger cap sizes do not exist in general as far as I know.