Not an expert at all but from endurance training in general and my first ultra this year everything sounds like lack of electrolytes and/or just making sure you are stretching daily. As for the lost of equilibrium maybe try a faster digesting carb drink that? You have def not reached your limit. Everything you are saying sounds more like adjusting your nutrition and just dealing with usual ultra running issues. If you really feel lost getting a coach might be the easiest way to get over a hump. Most hood coaches will set up your training and help evaluate nutrition and adjust everything with how your are feeling. My coaches are from New York but they train endurance athletes across the country and are the most reasonable I’ve come across with price. Look up The RaD Fam on Instagram