The President resigned and Board nominated me for the position and that position and I accepted. Question "I will now be both President and treasurer at the same time." I think this is a conflict of interest and must resigned my position as treasurer.
Typically, a person can hold two (2) or more offices in which case you can hold both the office of president and treasurer. However, you need to review your association's by-laws to determine if there is any prohibition against holding two (2) or more offices. By-laws, while permitting a person to hold two (2) or more offices, often restrict a person from holding the office of president and secretary.