is it permissable for one to paint the inner walls of their house during the ימי הספירה? i was told that it is forbidden to built a new house during sefirah, is this true? if so, would this extend to painting a house?

Shalom, Thank you for your question. In relation to painting your house - it is certainly allowed during the Omer Seferah period. One can also build a new house during this time. Even though there are opinions that do not allow moving into a new house, or major home renovations, because of the happiness involved (see Piskay Tshuvot, 493,1), there are great authorities who do permit it (see Tzits Eliezer 18,41). The Mishna Brurah rules that one may recite the Shehecheyanu blessing during this time, and I see no reason to rule more strictly than this. (It seems that many people confuse the laws of the 3 weeks, and the 9 days before the ninth of Av with the laws of the Omer, which are much more lenient). Blessings.