Unsure how to edit

There were a few months I was without my tablet. During that time I didn't track my period. Glow kept right on recording data, as it should but now, looking back I know those weren't the correct dates of my periods. I erased those dates but couldn't fill in the correct information, leaving it blank. Now my cycle phases page is messed up. Apparently my longest cycle was 90 days!?! Never in my life lol Is there Anyway to make note of my absence and lack of information? Or should I just make up period dates for that time frame? I doubt it'll effect anything current....