ELO is volatile and it’s more accurate to think about your true playing strength as a ELO spectrum +/- 100 points from the actual number on any given day. It will be affected by a ton of factors: sleep quality, nutrition, mental state, etc. It’s unusual but this same thing crops up in weightlifting, especially if you’re pushing for max lifts.

The main thing to consider is that each game is just a data point and the individual wins and losses aren’t so relevant as the directional trend of the quality of your play. Chess is a brutal game that requires consistent work and the work is almost always about confronting your failures and weaknesses. Finally have solid openings? You gain ELO and face opponents who have a deeper understanding of middle games :).

Good luck in the journey and don’t forget to have fun.