Hiya, I am an ex Pest Control Officer, You say you have been away for a while! this is a clue, whilst you are away any flea infestation would become far worse on your arrival back home as all those dear fleas have been starved and are now in feeding frenzy, that's the first possibility!!
The second is bed bugs! whilst away did you stay in a hotel, B&B etc they are prime suspects for Bed Bugs, Bed Bugs are usually identified by small specks of blood on you bedding, sheets pillows etc, to find the actual Bed Bugs you will need to search further, they will be found under the mattress buttons, under the cording around the mattress, behind and stitch work on the headboard, also look remove the headboard and check where the headboard makes contact with the bed, you will need a torch to look for them and they hide really well. Should you have either infestation call a pest control company and get them to treat it, you will not effectively eradicate either of these pests yourself, especially in the case of Bed Bugs!!
Good luck!!
Oh and if you find Bed Bugs do not throw away your bed!! the treatment is more successful to be able to treat the bed before removing it and all the Bed Bugs drop all over the floor and once the bed is treated there is no reason to dispose of it!!