My bowels always been irregular, now more constipated. when i do go it's a huge effort with little result and the smell is like mothballs. sorry. ta?

Bowel habit change: First, as you know, any change in bowel habits is a trigger for cancer screening, probably with colonoscopy, in a 51 year old (if it is due). Then continue with your usual constipation management: WATER, high fiber (bran, brown rice, whole wheat) diet, & daily exercise. The mothball smell is probably ammonia the result of dieting associated negative nitrogen balance and/or altered bowel flora.