Update a number from a previous date

I work for a company that assists Veterans and their Family members to get jobs and I am 99% done with a database I have created in Excel to track numbers so we can continue to get funding. A report also gets generated for the Consultant to see how they are doing with job posts and hirings period over period. Each rating period is (mid-month and end of month), which the numbers normally fluctuate between these two periods. A Consultant can have 322 active jobs posted for mid-month and 300 at the end of the month.

I am trying to get the accurate number to automatically populate the field when the new number is entered and carry over to the next reporting period. I have a consultant that started off January with 762 jobs posted then at the end of the month he gained 18 new job posts which brought him up to 780. What I have right now is adding those two numbers together and showing 1542 jobs posted and the number keeps increasing. Others decrease their numbers over a period, but it still adds everything together and gives me a high number.

Is there a way to have excel identify each consultant name and period and update these stats period over period when the new entry is made? 

I promise not to bother you again, I just need help getting this figured out.

Thank you