Question regarding powder formula

Genbot

Our LO was having issues with his bowel movements when we first started him on formula (they were infrequent, usually every 2 days and they were very painful for him and they were thick/pasty/cement-like).  My husband thought it might be bc of the powder formula and our lactation nurse also said that it might be better to use the Ready-To-Feed in the meantime, until his digestive system matured a bit.

 That being said, we decided that we would wait until the 2 month mark to try powder formula again (which is today).  We had just opened a brand new tub of powder formula right before Christmas and it has just been sitting in the pantry since we decided to use RTF for a while.  Since today is January 27, I'm guessing it has been about a month and the container says to use within one month of opening.  So, I'm looking for advice - would you use this powder formula, which he would probably finish within the next week or toss it?   Your input is greatly appreciated.  Many thanks.