Question

I adopted a 5 year old CockerSpaniel from the ASPCA 3 weeks ago and aside from some behavioral re- training, etc.... she is adjusting very well. My question is.... for the past week or so, she seems to be having a problem when she is having her bowel movement. She has approximately 3-4 movements per day which as of late hasn't been very solid, but when she seems to have finished, she remains in this position and seems to be straining to continue the movement... although there isnt anything. she had a bad case of diarhea the week prior which was very dark but as i hadn't changed her diet (iams dry food twice a day) assumed that she was still adjusting, etc.... her energy level is very high and active so not sure what could be going on unless she got worms while at the ASPCA? what would u recommend as first step? thanks