To be honest, trimming hair wont make much difference, its the health of the hair/scalp.
I cut my hair and i have really damaged hair.
I suggest the following;
Steaming your hair. I know it sounds odd but it adds moisture to your hair/scalp (Will help with both split ends and your dry scalp.
Basically, put a oil in your hair (scalp as well), use your fingertips to massage your scalp (dont rub it - that breaks hair). Wrap your head in cling film/shower cap and steam your hair. It works wonders!!
Morrocan oil is good but its dry oil. you want to start using a heavy oil (castor oil -mixed with olive oil or coconut oil) or just cocnut oil or amla oil. Do this overnight at least once a week.
I usually walk around the house with a oily head for 1 whole day and night and also if im washing my hair mid-week, i'll leave oil in it pre washing for atleast 30 mins.
Most importantly - get some healthy hair,skin, nails tablets from Holland and Barretts. I really noticed a difference with them!
Get a blood test done - Vit A/E/D deficiencies help cause bad hair/scalp.
I hope this works!!!
Oh, you can also get hydrating hair masks!!