My dog is acting weird? please help =(?

Well her name is Roxy, 6 years old, Bearded Collie and shes been acting weird lately... she wakes up yelping all the time and just isn't herself... She's been quite and isn't as happy as usual...she doesn't jump on us when we come home anymore...I'm really worried. Is she depressed or did she hurt her body in any way. Please help.=/ p.s. she sometimes just sits outside really quietly...weird and yelps when she tries to get inside