What Causes Sticky Residue On Hair After Wash?

hello,its about 7 months i have problem on my hair,after washing my hair i still feel there s some residue on my hair Like a gel,and after drying my hair and using dryer i can see my hair sticks to my hand, when i use hair straighter on my hair ,the place that straighter is on it acts like there s a glue on it... so much sticky, i tried washing with clarifying shampoos,dish washing liquid,Tide & moisturizer mix,kind of a local soap & etc, recently i visited a doctor in which gave me tea tree shampoo & tablets named biotin but unfortunately it doesn t work, i really need help, thank you,