EMB-175 First Officer reported a fumes event shortly after departure which dissipated initially and returned on descent to destination. After completing QRH procedure; priority ATC handling was requested and a safe landing to destination was completed.

Narrative

For me this event occurred one my 3rd leg of the day on day 5 of 6. For this flight; we were originally supposed to have Aircraft Y. When we got to the aircraft Maintenance was onboard investigating an open write up that previous crews had reported; fumes of unknown origin. Maintenance couldn't find the issue and we were assigned a new plane. We arrived to Aircraft X and soon departed. On climb out just after rotation; the captain and I noticed a smell but we both thought it was from the [prior aircraft] that took off prior to us. The smell went away quickly.Just before beginning the descent I had started to develop a slight headache. Upon starting descent a few moments later; we both started to smell the smell again. At this time the Captain said he had a headache and I responded that I had one as well. He then said he wanted to try something and gave me the radios (I was Pilot Flying and he was Pilot Monitoring) and donned the O2 mask for a couple of breaths. Then put his headset on and asked me to do the same. I took a couple of breaths from the mask and instantly felt better. I realized at that time we were definitely experiencing fumes of some unknown origin in the flight deck and that it wasn't us just being paranoid because of the fact that our original plane we were supposed to fly had this exact issue written up. I took my mask off and could really smell the fumes. I told the Captain I instantly felt better on the O2 and I can really smell the fumes now.The Captain immediately called for Smoke/Fire/Fumes QRC. At this time we were already descending on the STAR into our destination (maybe 15 min out). Captain took over the aircraft and radios while I ran the QRC then QRH. We started the QRH and requested special handling with ATC. The Captain called the FAs (Flight Attendants) and informed them of the situation and they could not smell any fumes in the cabin. We asked ATC to notify our Dispatch for us. We continued on with the QRH and stopped the QRH when we got to 'RAT Manual Deploy Lever ........ PULL'. We agreed to stop the QRH as we were less then 10min out from landing and did not want to put ourselves in an electrical emergency situation. Shortly after; we entered icing conditions and 'ICE CONDITION' along with 'STALL PROT ICE SPEEDS' appeared on EICAS. After loading ice speeds in we got a master caution for 'A-I WING FAIL'. After identify/cancel; Captain called for A-I WING FAIL QRH. We then realized the bleeds were out from the SMOKE/FIRE/FUMES QRH and stopped the A-I WING FAIL QRH. We broke out of the clouds about 5 seconds later and landed safely within a couple of minutes. We were met on the ground by Crash Fire Rescue and notified them that we did not need any assistance and were good to continue to the gate.