Welcome also had seven rebounds, three steals and two blocks for the Demons (10-9, 5-3 Southland), who had their largest lead at 78-45 with 4:22 to play.
Nicholls (5-12, 2-5) used an 8-0 run to get within 47-35 early in the second half, but Northwestern State answered with its own 8-0 run and led by no less than 17 from there.
Zeek Woodley added 13 points, Sabri Thompson scored 11 and Matt Killian 10 for the Demons. Jalan West handed out nine assists.
Ja'Dante' Frye had 11 points and Liam Thomas scored 10 to lead the Colonels. Nicholls scored seven straight after falling behind 20-9, but Northwestern State quickly pushed its lead back into double digits and scored five straight to close the half up 41-25.