Please help, my dog is really sad :(?

ok so i love my dog so much. he's going to be 10 this monday actually and he's a shih tzu. my dog is my life but we just can't get rid of his fleas. we've spent hundreads of dollars trying to get rid of them but they keep coming back. i haven't let my dog on my bed in a long time and i think he's really sad. i haven't been ignoring him but i miss snuggling with him and i think he does too. he always seems really sad. what should i do? i dont want my dog thinking i dont love him, because thats deffinately not the case. thanks