Well the whole feeling like shit, general fatigue, depression, etc could be a result of the PAWS which is only normal when coming off opiates or any addictive drug actually. You have to be prepared for them and learning how to deal with them will help alot as well. Eating healthy, exercising and various other activities such as lotsa sex help as well.
I generally sleep alot during the first few days of withdrawal (this is not including post withdrawal) then i do during the latter stages. From day 1 to 4 i have a hard time staying awake at all much less doing anything productive and then the insomnia kicks in and i feel even worse. No sleep (unless i take sleeping pills), feeling constantly fatigued, staring at the walls all night while chain smoking, etc.
As for feeling like shit the next day after dosing i would often wake up in withdrawal when i was shooting dilaudid since the stuff is so short acting. When i was shooting morphine or taking the instant release pills i would often go into WD within say 12 hours. Oxycodone is between dilaudid and morphine in terms of how long until i get sick again.
Keep your head up man you can beat it. Good luck