Dehydration doesn't "clear up" in a couple of days. If you aren't drinking enough and your urine is too concentrated (ie. dark), it only takes one big glass of water and an hour later your urine should be clearer.
If you are observing darker urine with your water intake staying more or less the same, chances are it's liver stress or changes in your body water balance, ie dehydration due to aas effects on the endocrine system. Especially if you are doing an only winstrol cycle you could have issues due to zero estrogen and winstrol by it self has substantial effects on water balance as it's somewhat anti estrogenic. Ofc aas effect renal flow, electrolytes, etc. However, dark urine is also not uncommon with oral aas due to liver stress. Check your liver values (bilirubin, ast, alt, alp, etc.) and check you kidneys along with a cbc.