Hi there congratulations on a good long fast. Hopefully the shoulder pain is due to repairing going on in there. It's possible it's due to lying on it badly during the night, especially as we get more bony and with low blood pressure/circulation overnight we can end up sleeping uncomfortably at times. Hot baths will often help these aches and pains.
The skin breaking out is classic detox and it is rarely pretty, be confident thought that your skin will be more than find afterwards, the fasting body leaves no scars!
And yes the longer you go the deeper the detox, though if you do subsequent fasts soon enough after another fast and with healthy raw eating in between you will find that the deep detoxing happens earlier, the body is capable of 'taking up where it left off' in previous fasts.
Don't be so hung up about the days you fast though, the body doesn't count them, if you're hungry you've done a complete fast, you may need more to completely cleanse your body but there is no rule saying 30 or 40 or 50 days is best. For some 20 days or less can be plenty, it just depends on the person and circumstances. If you have the time and energy for it aim to fast until true hunger returns, you just can't do better than that.